Method of casting hollow ingots



May 21, 1957 E. w. SMITH METHOD OF CASTING HOLLOW mco'r's Filed Nbkr. 29. 1954 2 Sheets-Sheet l May 21, 1957 E. w. SMITH METHOD OF CASTING HOLLOW INGOI'S 2 Sheets-Sheet 2 Filed Nov. 29, 1954 United States Patent METHOD OF CASTING HOLLOW INGOTS Eric Walter Smith, Sheffield, England, assignor to English Steel Corporation Limited, Shefiield, England, a British company Application November 29, 1954, Serial No. 471,840

Claims priority, application Great Britain February 15, 1954 1 Claim. (Cl. 22-200) This invention relates to .the manufacture of hollow ingots or castings of ferrous or non-ferrous metals, and is mainly concerned with simplifying and generally facilitating such manufacture.

Accordingly the invention provides a method of manufacturing hollow ingots or castings wherein an outer mould is filled to a preliminary level with liquid metal, and a core, adapted for radial contraction to accommodate shrinkage of the metal during cooling and solidification, is subsequently lowered into the mould from the top so as to displace the liquid metal level therein to the requisite height, said core being allowed to remain undisturbed in the mould for a predetermined period.

The invention further provides means for carrying out the foregoing method including a core composed of an outer sheath and an inner metallic supporting body adapted to permit radial contraction of the sheath under pressure.

In order that the invention may be clearly understood, several embodiments thereof will now be described in detail with reference to the accompanying drawings in which,

Figure. l is a cross-sectional side elevation showing one form of mould provided with a core in accordance with the invention,

Figure 2, is a plan view of Figure 1,

Figure 3 is a side elevational view showing an alternative form of core construction, and

Figure 4 is a diagrammatic plan view to an enlarged scale, showing a further alternative form of core construction.

The invention may be applied to hollow ingots or castings of any convenient size and shape as commonly cast in metal or refractory outer moulds, with or without feeder heads, and of any known conventional form. In the embodiment illustrated in Figures 1 and 2 of the drawings, the mould 1 is of octagonal cross-section and is provided with an open top 10. This open mould top In is conveniently fitted with a spider-like centralising device consisting, for example, of an annular ring 2 which is concentrically positioned over the open top of the mould by means of arms 3 extending radially from the ring and resting at their outer ends on the lip around the top of the mould. The arms 3 are adjustably secured in position by means of bolts 4 which extend through elongated slots 3a in the arms and engage apertured brackets 5 secured to the inside upper edge of the mould. Extending upwardly from the inner periphery of the ring 2 is a shallow funnel-like skirt member 6 which serves to guide a core of cylindrical or other shape into the mould through the ring 2 at the open top thereof, the ring then serving to centre the core Within the mould.

The core employed may take various forms and as illustrated in Figure 1, consists of an outer sheet metal cylindrical sheath 7 having the upper end open and the lower end closed by means of an end plate 7a, which may be fiat as shown, or concave, and is preferably welded to the sheath. Within the sheath 7 is a support- 2,792,605 Patented May 21, 1957 5 ICE ing body member 8 in the form of a solid metallic onepiece cylinder having an axial length approximately equal to the axial length of the surrounding sheath 7, and an outer diameter which is slightly smaller than the inside sheath diameter. Secured centrally in the top of the cylindrical body 8 is an eye bolt 9, and two registering apertured lugs or eye bolts 10 are secured in spaced apart positions to the top of the sheath 7, to receive a bar 11 which extends across the top of the cylindrical body 8and holds the latter in position in the sheath. The eye bolt 9 could, of course, be replaced by any other known means of suspension, and similarly the lugs 10 and retaining pin 11 could be replaced by any other known form of retaining device.

In an alternative core construction, the core supporting body may be constituted by a cylinder which is divided axially into segments 12, as illustrated in Figure 4. The segmental cylinder is again arranged to fit into an outer sheath similar to the sheath 7 shown in Figure 1 and the segments 12 are designed to contract radially to provide for shrinkage during solidification and cooling of the liquid metal in which the core is to be immersed.

In a further alternative core construction, the supporting body for the outer core sheath may be composed of a series of hollow discs 13 as illustrated in Figure 3. These discs 13 are threaded on to a centre spindle 14 and rest on an annular platform 15 at the lower spindle end. In this case the upper end of the spindle 14 is conveniently provided with an eye bolt 14a to facilitate suspension of the core. As a further alternative to this third embodiment, each disc may be composed of a number of axial segments to permit contraction of the supporting body as in the second embodiment illustrated in Figure 4.

All the cores as described are designed to provide an adequate chill through the casing sheath to the metal surrounding the core and, if desired, any of the cores can be bored to provide for circulation therethrough of a suitable coolant such as water or air whereby the rate of withdrawal of heat could be increased.

To carry out the method of the invention, the mould 1 is first filled to a required preliminary level with metal in a molten or liquid state. Whilst the metal in the mould is still in the liquid state, one of the cores as described is lowered into the mould from above, the core being accurately located in the mould by means such as the centralising device illustrated. Any convenient means can be utilised for lowering the core into the mould, the suspension means at the top of the core body being utilised to facilitate this operation.

The overall dimensions of the composite core are such that, when the core is in position in the mould, the level of the liquid metal will de displaced up the mould to the required height, and into the feeder head where such a head is employed. Once positioned in the mould, the core is allowed to remain undisturbed for a determined period. In cases where a core having a solid cylindrical supporting body is employed as shown in Figure 1, this body 8 is then released from the sheath, by removing the transverse bar 11 from the registering lugs 10, and the supporting body 8 is then withdrawn leaving the sheath 7 in situ. If further extraction of heat is required, this can readily be accomplished by inserting a further supporting body into the sheath of slightly smaller external diameter than the body originally utilised. This process of withdrawal and replacement of the supporting body can be continued until the ingot has solidified.

In cases where a core having a supporting body divided into axial segments as shown in Figure 4 is employed, an identical method to the foregoing is adopted except that the core supporting body need not necessarily be withdrawn and replaced by a smaller diameter body during solidification since the core supporting body is itself designed to be capable of radial contraction to accommodate shrinkage.

In the case of the composite core having a supporting body composed of hollow discs as shown in Figure'3, the method employed is again as described, further heat extraction being accomplished where necessary by utilising a supporting body having discs of smaller diameter, Again, however, if the discs are arranged for radial con-- traction, replacement of the supporting body will normally be unnecessary.

It will be appreciated that, whilst octagonal section moulds'and concentric cylindrical cores have been described and illustrated, the invention is by no means limited to such configuration of the mould or cores nor does the core necessarily have to be located concentrically within the mould.

I claim:

A method of casting hollow ingots comprising the steps of filling a mould to a predeterminedlevel with liquid metal, subsequently inserting a metallic heat absorbing core removably encased within a loose fitting thin sheet metal jacket into the liquid metal in said mould, from the top of the latter, to form the ingot bore, replacing the inserted core at least once by a smaller diameter core for the purpose of further heat extraction and finally withdrawing the last inserted core when solidification of the liquid metal has taken place, the jacket being left in situ in the ingot bore.

References Cited in the file of this patent UNITED STATES PATENTS 

